This invention relates generally to gas turbine engines and more particularly to components for actuation of variable stator vanes in the compressor of such engines.
A gas turbine engine includes a compressor used to pressurize intake air which then flows to a downstream combustor and one or more turbines. A typical compressor includes a series of stages, each stage including a row of stationary stator vanes and a row of rotating compressor blades.
In some gas turbine engines, one or more stages of the stator vanes are variably actuated. An outer trunnion or spindle of each vane passes through the stator case and is coupled to a lever arm. A distal end of each lever arm is joined to an actuation ring through a pin that engages a hole in the actuation ring. The actuation ring is in turn connected to a vane actuator.
In a prior art bushing design, a generally cylindrical bushing is inserted into a circular bore from an outboard position in a radially inward direction. The bushing has a flange at its outer end which locates against the housing and prevents the bushing from moving further radially inboard. The inner end of the bushing has a “barbed” configuration. The inboard end of the bore has a counterbore which forms a retention shoulder. Upon insertion, the barbed end passes by the retention shoulder, thus preventing extraction of the bushing in a radially outward direction.
One problem with this design is that in operation, cracks can form between the flange and the bushing, causing the flange to separate. This would allow the bushing to drop radially inward and no longer be properly located. This condition can result in improper operation or damage to the components.